Radio loud-speaker



Dec. 30, 1930.

B. GROOM RADIO LOUD SPEAKER Filed April 29, 1929 Patented De e 3o, 1930 I l UNITED STATES "PATENT, OFFICE BRYAN G ROOM, OF GALASHIELS, SCOTLAND nenro LOUD-SPEAKER Application filed .A rn 29,1929, Serial No. 358,805, and invGreat Britain may 14, 1928.

This invention relates to radio loud speak? ers of the kind including a diaphragm and a non-resonant baflle which is so locatedrelatively to the diaphragm that it serves'to re- 5 strict the passage of air from one side of the diaphragm to the other. I i

In connection with loud speakers of this type it is usual so to mount the baffle that it surrounds the diaphragm. The effect of so mounting the baffle is to strengthen the bass notes and it is found that excessively strong bass notes are objectionable to certain listeners. V g

An object of the invention is to provide a loud speaker incorporating means for Varying the strength of the bass notes relatively to that of the treble notes.

The invention provides aloud speaker in which the diaphragm and the battle are telescopically related and in which the end of the battle nearest the diaphragmis located withinthe diaphragm or within an extension thereof.

Three embodiments of the invention are illustrated diagrammatically in the drawing in which Fig. 1 is a section of a loud speaker incorporating a conical diaphragm and a coni- .Cal bafile provided with cylindrical extensions, Fig. 2 a section of a loud speakerv incorporating a fiat diaphragm having a cylindrical extension accommodating a cylindrical extension of a conical bathe and Fig. 8 a section of a loud speaker incorporating two nested cones.

The loud speaker shown includes a diaphragm 1 carrying a coil drive 2. A usual pot magnet is denoted at 3, the field winding of which is indicated conventionally at 4: (Figs. 1 andv2). A non-resonant bafile denoted at5 is as usual so located relatively to the diaphragm 1 that itserves torestrict the passage of airfrom one side of the diaphragm to the other. In the three embodiments illustrated the diaphragm 1 and the battle 5 are telescopically related and the end of each bafile nearest the corresponding diaphragm 1 is located either'within the diaphragm 1 or within an extension thereof.

According to the embodiment illustrated in Fig. 1 there is employed a conical diaphragm 1 having a cylindrical tubular extension 6 and a conical non-resonant bafile 5 having a cylindrical, tubular extension 7, the

extension 7 being located within and in close proximity to the extension 6.

, In the embodiment lllustrated in Fig. 2 a flat diaphragm 1 is provided with acylindrical extension 6 and a conical bafile 5 having. a cylindrical extension 7 which is located within and in close proximity to the extension 6. According to the embodiment illustrated in Fig. '3 the diaphragm 1 and 'thebafiie 5 comprise two nested cones, the cone constitilting the battle 5 being located within the cone constituting the diaphragm 1. It will be seen that, in the forms shown in Figs. 1 and 2 thediaphragm extension overlaps the bafiie extension andthat the efliciency of the seal will depend on the ex tent of the overlap.

I claim L 1 A radio loud speaker of the class described comprising, in combination, a diaphragm and a non-resonant bafile arranged in telescopic relationship with said baflle and with the end nearest said diaphragm within said diaphragm. 1

2 A radio loud speaker of the class de-' scribed comprising, in combination, a diaphragm having a tubular extension and a non-resonant balile having a second extension arranged in telescopic relationship with and locatedwithin said firstextension.

3. A radio loud speaker of the class descrlbed comprising, in combination, a diaphragm having a cylindrical tubular extension and a non-resonant baflie having a second extension arranged in telescopic rela tlonship with and located within said first extension.

In testimony whereof I have signed my name to this specification.

1 BRYAN GROOM. 

